88D-Link DIR-628 User Manual
Section 6 - Troubleshooting
 
You should start at 1472 and work your way down by 10 each time. Once you get a reply, go up by 2 until you get a 
fragmented packet. Take that value and add 28 to the value to account for the various TCP/IP headers. For example, 
lets say that 1452 was the proper value, the actual MTU size would be 1480, which is the optimum for the network 
we’re working with (1452+28=1480). 
Once you find your MTU, you can now configure your router with the proper MTU size. 
To change the MTU rate on your router follow the steps below: 
• Open your browser, enter the IP address of your router (192.168.0.1) and click OK. 
• Enter your username (admin) and password (blank by default). Click OK to enter the web configuration 
page for the device. 
• Click on Setup and then click Manual Configure. 
• To change the MTU enter the number in the MTU field and click Save Settings to save your settings. 
• Test  your  email.  If  changing  the  MTU  does  not  resolve  the  problem,  continue  changing  the MTU  in 
increments of ten.